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UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  No.  132 


THE    EFFECT    OF    SELECTION    UPON    CERTAIN 

PHYSICAL   CHARACTERS    IN   THE 

CORN   PLANT 


BY  LOUIE  H.  SMITH 


URBANA,   ILLINOIS,   FEBRUARY,   1909 


SUMMARY  OF  BULLETIN  No.  132 

1.  This  bulletin   reports   the   results   of   experiments   in  breeding  corn   to 
modify  certain  physical  characters  in  the  plant;  namely,   (1)   Height  of  ear  on 
stalk,  and  (2)  Declination  of  ear  from  stalk. 

2.  By  breeding  a  variety  in  opposite  directions  two  strains  of  corn  have 
been  produced  in  one  of  which  ears  are  now  borne  about  three  feet  higher  on 
the  stalk  than  in  the  other  strain.  Page  53 

3.  Selecting  simply  "with  reference  to  height  of  ear  has  induced  some  pro- 
nounced secondary  effects  upon  the  plant.    The  plants  of  the  high-ear  strain 
have  longer  stalks,  longer  internodes,  a  greater  total  number  of  internodes  and  a 
greater  number  of  internodes  below  the  ear  than  have  those  of  the  low-ear 
strain.  Page  53 

4.  There  is  a  noticeable  difference  in  the  length  of  growing  period  in  the 
two  strains,  early  maturity  being  associated  with  the  smaller  type  of  plant  of  the 
low-ear  strain.  Page  56 

5.  Comparative  tests  for  yield  thus  far  indicate  no  great  difference  between 
the  two   strains  in  production   of   grain  but   the   high-ear   strain  produces   the 
more  fodder.  Page  56 

6.  Experiments  in  selection  for  erect  and  declining  ears  indicate  that  the 
declining  habit  is  a  character  which  can  be  influenced  by  breeding.          Page  58 

7.  No  significant  effect  from  this  selection  has  yet  been  produced  on  the 
yield.  Page  58 

8.  The  length  of  shank  appears  to  be  the  principal  factor  in  determining 
the  declining  habit.  Page  60 

9.  The  practical  advantages  in  the  declining  ear  are  found  in  the  better 
protection  from  rain  and  the  greater  convenience  in  handling  at  harvest. 

Page  60 


48 


PLATK   1. — REPRESENTATIVE   STALKS  TAKEN   FROM  THE  HIGH-EAR  AND  LOW-EAR 
PLOTS  IN  THE  FIFTH  GK.NK.RATION. 


Acknowledgment  is   due  and  is   hereby  gratefully  given   to   the   following 
persons  who  have  at  various  times  been  responsible  for  the  conduct  of  the  ex-, 
periments  reported  in  tHis  bulletin : — 

Doctor  E.  M.  East,  now  agronomist  at  the  Connecticut  Experiment  Sta- 
tion; Mr.  H.  H.  Love,  now  assistant  in  experimental  plant-breeding  at  Cornell 
University  and  Mr.  C.  H.  Myers,  assistant. in  chemistry  at  the  Illinois  Agri- 
cultural Experiment  Station. 


50 


THE    EFFECT    OF    SELECTION    UPON    CERTAIN 

PHYSICAL   CHARACTERS   IN   THE 

CORN   PLANT 

By  LOUIE  H.  SMITH,  Assistant  Chief  in  Plant  Breeding 

Among  the  various  lines  of  investigation  in  corn  breeding  at  this 
Station  a  series  of  experiments  has  been  conducted  for  a  number  of 
years  to  test  the  possibility  of  modifying  by  continuous  selection  certain 
physical  characters  of  the  corn-plant.  It  is  the  purpose  of  this  bulletin 
to  report  the  results  obtained  in  the  experiments  to  influence  two  such 
characters;  namely,  the  height  at  which  the  ear  is  borne  upon  the 
stalk,  and  the  position  of  the  ear  with  reference  to  its  declination 
from  the  stalk  at  maturity. 

HIGH  AND  LOW  EARS 
GENERAL  PLAN  OF  THE  EXPERIMENT 

In  the  autumn  of  1902  from  an  ordinary  field  of  Learning  corn 
two  sets  of  ears  were  selected,  one  of  which  represented  ears  growing 
high  on  the  stalk  and  the  other  those  borne  low  down  on  the  stalk. 
These  two  sets  of  ears  were  planted  the  following  spring  in  separate 
breeding  plots,  and  selection  for  high  ears  and  for  low  ears,  from  the 
respective  plots,  has  been  made  each  year  since. 

As  this  experiment  was  undertaken  in  part  for  the  purpose  of 
demonstration,  the  two  plots  have  always  been  planted  end  to  end  for 
the  sake  of  convenient  inspection  altho  it  is  recognized  that  such  close 
proximity  of  different  breeding  plots  may  not  represent  ideal  condi- 
tions for  the  best  results  on  account  of  the  danger  of  inter-crossing. 
This  difficulty  has  however  been  practically  eliminated  by  taking  the 
precaution  always  to  confine  the  selection  of  seed  ears  to  plants  located 
toward  the  outer  ends  of  the  plots.  If  perchance  any  such  inter- 
crossing has  occurred  in  these  plots  the  remarkable  progress  which 
the  results  show  has  been  made  in  spite  of  such  a  handicap. 

The  plots  are  planted  according  to  our  regular  ear-row  system, 
and  productiveness  is  made  the  basis  of  the  first  selection.  Thus,  only 
the  best  yielding  plot-rows  are  selected  and  from  these  rows  the  seed 
ears  are  chosen  with  reference  to  the  height  at  which  they  are  borne 
upon  the  stalk,  only  good  sound  ears  being  taken. 

The  number  of  ears  planted  in  the  breeding  plot  has  varied  in 
the  different  years  but  the  plan  now  followed  is  to  have  24  rows, 

51 


52 


BULLETIN  No.  132 


[February, 


each  row  planted  from  an  individual  ear.  Alternate  rows  are  detas- 
seled  and  four  seed  ears  are  taken  from  each  of  the  best  six  detasseled 
rows,  arranging  the  order  of  planting  the  following  year  with  refer- 
ence to  the  relationships  of  these  seed  ears  so  as  to  avoid  as  much  as 
possible  any  close-breeding. 

THE  DATA 

The  data  are  obtained  by  taking  the  observations  on  the  plants 
at  certain  intervals,  every  third  hill,  in  each  plot  row,  so  that  the 
yearly  results  given  are  derived  from  the  averages  of  large  numbers 
of  observations,  thus  securing  a  very  fair  representation  of  the  plots. 

These  observations  have  included  the  following  points:  (1)  the 
height  of  ear,  (2)  the  total  length  of  stalk  above  ground,  (3)  the 
node  at  which  the  ear  is  borne  (counting  from  the  ground  upward), 
and  (4)  the  total  number  of  internodes  of  the  stalk. 

SUMMARY  OF  THE  RESULTS 

From  the  records  of  these  observations  the  following  table  is 
constructed  by  bringing  together  the  averages  for  each  generation, 
placing  the  corresponding  data  of  both  plots  side  by  side  for  con- 
venient comparison. 

Table  No.  1.     CORN  BREEDING  FOR  HIGH  EARS  AND  FOR  Low  EARS 
(General  averages  of  crops  produced  in  each  of  six  generations) 


Year 

Height  of  ear 
(inches) 

Height  of  plant 
(inches) 

Number  of  inter- 
nodes  below  ear 

Total  number  in- 
ternodes of  stalk 

High- 
ear  plot 

Low- 
ear  plot 

High- 
ear  plot 

Low- 
ear  plot 

High- 
ear  plot 

Low- 
ear  plot 

High- 
ear  plot 

Low- 
ear  plot 

1903  

56.4 
50.3 
63.3 
56.6 

72.4 
57.3 

42.8 
38.3 
41.6 
25.5 
33.2 
23.1 

113.9 
106.2 
128.4 
116.3 
130.4 
114.0 

102.5 
97.4 
106.5 
86.0 
99.7 
79.3 

8.5 
7.5 
8.2 
9.0 
9.2 
8.2 
1 

7.2 
6.2 
6.5 
5.9 
5.8 
4.7 

15.4 
14.5 
15.4 
15.1 
16.3 
15.5 

13.9 
13.0 
13.6 
11.0 
13.0 
11.5 

1904  

1905  

1906  

1907..  

1908  

The  growth  is  of  course  affected  by  environmental  conditions 
as  well  as  by  hereditary  tendencies  and  the  absolute  height  of  ear 
on  the  stalk  as  well  as  height  of  plant  will  be,  so  to  speak,  a  resultant 
of  these  two  factors,  varying  from  year  to  year  in  accordance  with 
soil  and  season.  But  by  having  the  high-ear  and  low-ear  plots  grow- 
ing side  by  side  each  year  we  may  eliminate  to  some  extent  at  least 
the  environmental  factor  and  get  a  measure  of  the  effect  really  due 
to  heredity. 

A  clearer  view  of  the  general  progress  of  the  breeding  is  obtained 
by  observing  the  differences  between  the  two  plots  in  average  height 
of  ear,  etc.,  for  each  year  as  derived  from  the  preceding  table.  These 
differences  are  found  to  run  as  follows, 


1909]       EFFECT  OF  SELECTION  ON  PHYSICAL  CHARACTERS  IN  CORN  PLANT 


53 


Table  No.  2.     AVERAGE  DIFFERENCES  IN  CROP  EACH  GENERATION  RESULTING  FROM 
SELECTION  FOR  HIGH  EARS  AND  FOR  Low  EARS 


Year 

Difference 
in  average 
height  of 
ear 
(inches) 

Difference 
in  average 
height  of 
plant 
(inches) 

Difference 
in  average 
number  of 
inter  nodes 
below  ear 

Difference 
in  average 
number  of 
internodes 
of  stalk 

1903  

13.6 

11.4 

1.3 

*  1.5 

1904  .  .  .  v  

12.0 

8.8 

1.3 

1.5 

1905   

21.7 

21.9 

1.7 

1.8 

1906  

31.1 

30.3 

3.1 

4.1 

1907  

39.2 

30.7 

3.4 

3.3 

1908  

34  2 

34.7 

3.5 

4.0 

These  figures  show  in  a  striking  manner  the  way  in  which  the 
crop  has  responded  to  the  seed  selection.  Thus  we  see  in  the  second 
column  of  Table  2  that  up  to  the  last  generation  there  has  been  in  general 
a  gradually  increasing  difference  in  height  of  ears  in  these  two  strains 
according  to  the  breeding  until  this  difference  amounts  to  over  three 
feet.  It  will  be  noticed  that  in  the  last  generation  instead  of  an 
advance  as  heretofore  there  appears  to  be  a  slight  regression.  This 
however  may  be  accounted  for  in  the  fact  that  the  season  of  1908 
was  very  unfavorable  to  corn  in  this  locality,  so  that  the  large  plants 
of  the  high-ear  strain  suffered  more  in  their  development  from  the 
adverse  conditions  than  did  those  of  the  low-ear  strain. 

Besides  the  direct  effect  upon  the  height  of  ear  the  data  bring 
out  clearly  a  very  pro'nounced  secondary  effect  produced  by  the  selec- 
tion. Selecting  the  seed  simply  with  reference  to  the  height  at  which 
the  ear  is  borne  has  resulted  in  an  effect  upon  the  height  of  the  plant 
so  that  the  stalks  of  the  high-ear  plot  now  average  nearly  three  feet 
taller  than  those  qf  the  low-ear  plot. 

It  is  interesting  to  note  that  in  this  effect  upon  the  height  of 
ihe  plant  two  factors  have  been  involved,  namely  the  number  of  inter- 
nodes  and  the  average  length  of  each  internode.  It  is  further  evident 
from  the  data  that  these  same  two  factors  have  been  effective  in 
determining  the  height  of  ear.  That  is  to  say,  in  selecting  for  high 
ears  we  have  incidentally  selected  those  plants  having  longer  inter- 
nodes  and  bearing  their  ears  at  a  higher  node,  while  in  the  case  of 
the  low  ears  we  have  been  selecting  plants  having  shorter  internodes 
and  bearing  their  -ears  at  a  lower  node. 

Perhaps  the  most  significant  of  all  as  throwing  light  upon  broader 
problems  of  heredity  is  the  fact  brought  out  by  these  results  that 
the  corn  has  not  only  responded  to  the  selection,  but  there  has  been 
a  gradual  progressive  shifting  of  the  types  so  that  even  in  the  fourth 
generation  the  average  height  of  ears  in  the  one  strain  is  more  than 
twice  that  in  the  other.  Thus  we  find  in  its  behavior  in  this  regard 
a  principle  of  breeding  quite  in  accord  to  that  observed  in  connection 
with  the  breeding  of  corn  to  modify  the  composition  of  the  grain. 
(See  bulletins  119  and  128.) 


54 


BULLETIN  No.  132 


{February, 


PLATE  2.— IN  THE  HIGH-EAR  PLOT  AFTER  FIVE  YEARS  OF  BREEDING, 


1909]        EFFECT  OF  SF.LF.CTTON  ON  PHYSICAL  CHARACTF,RS  IN  CORN  PLANT  55 


PLATE  3. — IN  THE  LOW-EAR  PLOT  AFTER  FIVE  YEARS  OF  BREEDING. 


56  BULLETIN  No.  132  [February, 

We  have  in  these  results  a  striking  illustration  of  the  faithful 
manner  in  which  corn  responds  to  continuous  systematic  selection 
for  a  particular  characteristic  and  an  indication  of  the  possibilities 
for  the  improvement  of  this  all-important  crop  through  judicious 
and  persistent  selection  of  the  seed  for  definite  purposes. 

EFFECT  ON  MATURITY 

Selection  for  high  ears  and  low  ears  has  resulted  in  a  notable 
difference  in  the  maturity  of  the  two  strains.  This  is  especially 
apparent  at  the  time  of  flowering.  It  was  observed  the  last  two 
seasons  that  the  tassels  were  well  developed  in  the  low-ear  plot  before 
they  appeared  in  the  high-ear  plot.  The  low-ear  plot  was  apparently 
about  a  week  in  adyance  of  the  high-ear  plot  at  this  stage. 

It  is  interesting  to  note  in  this  connection  that  the  same  principle 
has  been  observed  in  regard  to  earliness  in  other  crops.  For  example 
in  breeding  cotton  where  early  maturity  is  desired  in  order  to  escape 
damage  by  the  boll  weevil  it  has  been  found  that  earliness  is  to  be 
secured  by  .selecting  plants  of  low  growing  habit  with  few  and  short 
internodes  and  with  bolls  borne  low. 

Again  in  the  case  of  the  pea,  the  Swalof  Plant-Breeding  Station 
recommends,  for  earliness,  to  select  such  plants  as  possess  but  few 
internodes  below  the  first  flowers,,  and  the  statement  is  made  that 
the  fewer  the  total  number  of  internodes*the  earlier  is  the  ripening. 

As  is  well  known  our  early  varieties  of  corn  are  characterized 
by  relatively  small  plants  while  those  of  late  maturity  usually  have 
large  plants  with  tall  stalks  requiring  a  longer  growing  season  in  which 
to  complete  the  vegetative  life. 

Thus  our  observations  are  quite  in  accord  with  what  appears  to 
be  a  general  principle  that  applies  not  only  to  corn  but  also  to  other 
crops ;  that  is,  early  maturity  is  characterized  by  few  and  short  inter- 
nodes with  fruit  borne  low. 

One  of  the  most  important  questions  before  the  attention  of 
corn  growers  and  corn  breeders  at  present  is  that  of  maturity.  The 
demand  is  for  grain  that  will  grade  better  in  the  market,  keep  better 
in  storage  and  transportation,  and  germinate  better  when  planted  in 
the  field,  and  our  problem  is  the  difficult  one  of  inducing  earliness 
without  sacrificing  yield. 

EFFECT   ON    YIELD 

The  question  naturally  follows  as  to  how  the  yield  has  been 
affected  by  the  selection  for  these  two  opposite  characteristics. 

In  the  last  three  years  seed  has  been  carried  from  each  of  these 
breeding  plots  to  our  variety  test  plots,  where  conditions  of  soil  and 
culture  are  made  as  uniform  as  possible  for  obtaining  comparable 
yields.  » 

The  results  of  this  test  given  in  terms  of  bushels  of  shelled  corn 
per  acre  are  as  follows. 


1909]        EFFECT  OF  SELECTION  ON  PHYSICAL  CHARACTERS  IN  CORN  PLANT  57 

Year  High-ear  strain  Low-ear  strain 

1906  72.4  72.6 

1907  64.5  68.8 

1908  60.9  59.5 

Thus  we  see  that,  in  spite  of  the  much  smaller  size  of  the  low- 
ear  plant,  in  production  of  grain  this  strain  compares  very  favorably 
with  the  high  ears.  The  evidence  from  a  three-year  trial  of  yields  is 
rather  too  limited  to  warrant  sweeping  deductions,  but  the  results  cer- 
tainly indicate  that  by  careful  attention  to  the  selection  of  good  seed 
ears  it  is  quite  possible  to  maintain  the  rate  of  yield  from  the  smaller, 
quicker  maturing  plant  of  the  low-ear  type. 

Some  of  our  leading  corn  growers  are  advocating  a  reduction 
in  the  standard  size  of  ear  in  the  belief  that  a  longer  growing  season 
is  necessary  for  the  production  of  the  large  type  of  ear  that  has  been 
set  for  the  ideal,  and  that  striving  to  attain  this  ideal  has  resulted 
in  lateness  in  maturity  of  some  of  our  best  varieties.  This  is  to 
some  extent  plausible;  but  it  would  seem  that  the  lesson  brought 
out  by  these  experiments  is  that  attention  should  be  given  to  size  of 
plant  as  well  as  to  size  of  ear  and  that  by  selecting  well  developed 
ears  borne  comparatively  low  on  the  stalk  of  smaller  plants  we  shall 
accomplish  more  in  inducing  earliness  at  possibly  less  sacrifice  in 
yield  than  in  attempting  to  regulate  the  size  of  ear  alone. 

ERECT   AND   DECLINING   EARS 

Among  the  very  noticeable  variable  characters  to  be  seen  in  any 
field  of  mature  corn  is  the  manner  in  which  the  ear  is  borne  with 
reference  to  the  angle  which  it  makes  with  the  stalk.  A  few  minutes 
observation  will  discover  all  degrees  of  declination  of  ears,  varying 
from  those  which  stand  almost  perfectly  upright  to  those  that  hang 
straight  downward. 

In  order  to  determine  to  what  extent  this  character  might  be  in- 
fluenced by  breeding  and  what  value  if  any  attaches  to  it,  selection 
was  begun  in  1903  for  "erect"  and  for  "declining"  ears.  For  this  ex- 
periment two  sets  of  ears  were  taken  according  to  angle  of  declination 
at  harvest  time  from  our  "Illinois  High-Oil"  breeding  plot,  a  strain 
which  had  been  under  selection  for  seven  generations  for  increase  in 
oil  content. 

These  two  sets  of  ears  were  planted  in  two  corresponding  breed- 
ing plots  and  selection  has  been  kept  up  in  these  two  directions  since 
that  time.  The  breeding  plots  have  been  conducted  on  the  same 
general  system  as  the  "High-Ear"  and  "Low-Ear"  plots  just  described, 
planting  by  the  ear-row  method,  detasseling  alternate  rows  and  basing 
the  first  selection  upon  yielding  capacity. 

THE  DATA     * 

Records  have  been  taken  each  year  by  measuring  the  angle  that 
the  ear  makes  with  the  stalk  on  which  it  is  borne  just  before  the 
harvest.  If  the  ear  stands  erect  the  angle  is  recorded  as  0,  if  hori- 


58 


BULLETIN  No.  132 


[February, 


zontal  it  is  90  degrees,  if  hanging  straight  downward  it  is  180  degrees, 
and  all  intermediate  positions  are  recorded  in  degrees  corresponding. 

An  index  having  a  movable  pointer  and  a  half  circle  marked  off 
in  degrees  has  been  found  useful  in  taking  these  data.  The  measure- 
ments are  taken  when  the  corn  is  ripe  at  certain  definite  intervals  in 
every  row,  so  that  the  results  obtained  represent  a  fair  average. 

From  the  records  thus  obtained  the  following  averages  have 
been  taken  which  will  serve  to  show  very  well  the  general  progress 
of  the  work. 

Table  3.    CORN  BREEDING  FOR  ERECT  EARS  AND  FOR  DECLINING  EARS 
(Degrees  of  declination  from  the  perpendicular) 


Average  of  seed 

Average  of  crop 

Year 

Erect- 

Declining- 

Difference 

Erect- 

Declining- 

Difference 

ear 

ear 

between 

ear 

ear 

between 

strain 

strain 

strains 

strain 

strain 

strains 

1904.. 

20.0° 

180.0° 

160.0° 

42.0° 

45.0° 

3.0° 

1905.. 

16.7° 

180.0° 

163.3° 

62.2° 

117.1° 

54.9° 

1906.. 

15.0° 

180.0° 

165.0° 

49.5° 

76.2° 

26.7° 

1907.. 

12.8° 

180.0° 

167.2° 

42.3°    • 

81.6° 

39.3° 

1908.. 

7.2° 

176.0° 

168.8° 

46.0° 

88.5° 

42.5° 

It  will  be  noticed  that  in  the  first  generation  the  response  to  the 
selection  was  very  slight  as  indicated  by  the  results  in  the  last  column,, 
where  the  figures  show  the  average  difference  each  year  between  the 
two  plots.  In  the  second  year  this  response  was  very  much  greater, 
in  fact  the  results  show  that  it  was  more  marked  that  year  than  it  has 
been  since.  The  conditions  of  that  season  seem  to  have  been  excep- 
tionally favorable  for  declining  ears  as  seen  from  the  results  in  both 
plots.  After  the  second  year  the  average  difference  in  the  crops  has 
steadily  increased.  On  the  whole  we  find  that  we  have  been  able  to 
influence  this  character  to  a  considerable  extent  in  the  five  years  of 
breeding;  and  with  the  exception  of  1905  it  has  responded  almost 
as  faithfully  and  regularly  to  selection  as  in  the  case  of  the  -height 
of  ear. 

EFFECT   ON    YIELD 

In  regard  to  the  influence  of  this  selection  upon  the  yield,  it  may 
be  said  that  no  decided  effect  is  yet  apparent.     Following  are  the 
results  of  two  years'  trial  in  the  variety  test  plots  given  in  bushels 
of  shelled  corn  per  acre. 
1  Year  Erect-ear  strain  Declining-ear  strain 

1907  69.7  65.8 

1908  60.2  62.2 

DETERMINING  FACTOR  IN  THE  ANGLE  OF  DECLINATION 

The  manner  in  which  the  erect  or  declining  character  is  affected 
is  of  interest  in  this  connection. 


1909]        EFFECT  OF  SELECTION  ON  PHYSICAL  CHARACTERS  IN  CORN  PLANT  59 


PIRATE  4. — AFTER  FIVE  GENERATIONS  THE  AVERAGE  AMGLE  OF  DECLINATION  IN  THE 
ERECT-EAR  STRAIN  is  46°.   JN  THE  DECLINING  EAR  STRAIN  IT  is  88.5° 


60  BULLETIN  No.  132  [February, 

In  order  to  obtain  some  definite  information  on  this  matter  a 
detailed  study  was  made  upon  the  crop  of  1907  and  it  was  found  by 
measuring  large  numbers  of  specimens  from  both  plots  that  the  ear- 
branch  or  shank  was  on  the  average  almost  twice  as  long  in  the 
declining-ear  strain  as  in  the  erect-ear  strain,  the  averages  for  that 
year  being  about  12  inches  and  7  inches  respectively.  The  difference 
found  in  diameter  of  shank  was  so  slight  as  to  be  insignificant. 

This  indicates  that  in  producing  the  declining  ear  we  have  really 
been  selecting  those  plants  which  have  longer  shanks. 

In  this  study  a  count  was  made  of  the  number  of  internodes  of 
the  shank  and  also  of  the  number  of  husks.  As  might  be  expected 
the  longer  shanks  of  the  declining  ears  had  an  average  of  a  slightly 
larger  number  of  internodes  and  correspondingly  a  larger  average 
number  of  husks. 

PRACTICAL  CONSIDERATION 

Most  corn  growers  are  of  the  belief  that,  in  general,  declining 
ears  are  preferable,  especially  in  a  wet  autumn,  on  account  of  the 
better  protection  from  rain  and  the  consequent  liability  to  decay.  As 
a  matter  of  fact  it  has  been  noticed  for  a  number  of  years  that  there 
has  been  more  unsound  corn  in  the  erect-ear  plot  than  in  the  declining- 
ear  plot.  In  1908  a  count  was  taken  of  the  number  of  mouldy  or 
rotted  ears  in  each  plot,  and  the  records  show  5.33  percent  of  the 
unsound  ears  in  the  erect-ear  plot  and  only  2.05  percent  in  the  de- 
clining-ear plot.  It  should  be  considered  in  this  connection  that  this 
was  an  exceptionally  dry  autumn. 

In  some  seasons  the  seed  from  the  erect-ear  plot  has  shown 
markedly  poorer  germination  but  this  is  not  always  the  case,  depend- 
ing naturally  upon  the  seasonal  conditions  with  regard  to  rain  and 
freezing  during  the  fall. 

According  to  the  prevailing  opinion  there  is  another  advantage 
in  the  declining  ear  and  this  is  the  greater  convenience  that  such  an 
ear  affords  in  husking  from  the  standing  stalk.  If  however  the  corn 
is  harvested  with  a  machine  the  hanging  ear  is  likely  to  cause  trouble, 
especially  if  the  shank  is  very  long. 

So  it  seems  that  in  this  particular  the  case  is  like  that  of  a  great 
many  others,  the  desirability  of  the  character  will  depend  upon  cir- 
cumstances, and  it  is  of  interest  to  know  that  the  character  is  suscep- 
tible of  modification  and  to  a  large  extent  under  the  control  of  the 
breeder. 


LIST  OF  BULLETINS  OF  THE  ILLINOIS  EXPERIMENT  STATION  RELATING  TO  CORN 

BREEDING 

*Bulletin  No  21.     Horticulture;  A  General  Report;  Corn  Crossing;  Sweet  Corn, 

Thickness  of  Planting,  1891 ;  the  Late  Season  and  the  Corn  Crop. 
*Bulletin  No.  53.    The  Chemistry  of  the  Corn  Kernel. 

*  Bulletin  No.  55.     Improvement  in  the  Chemical  Composition  of  the  Corn  Ker- 

nel. 
^Bulletin  No.  63.     Seed  Corn  and  Some  Standard  Varieties  for  Illinois. 

*  Bulletin  No.  82.    Methods  of  Corn  Breeding. 

Bulletin  No.  87.     The  Structure  of  the  Corn  Kernel  and  the  Composition  of  its 

Different  Parts. 
Bulletin  No.  100.     Directions  for  the  Breeding  of  Corn,  Including  Methods  for 

the  Prevention  of  In-Breeding. 

Bulletin  No.  128.     Ten  Generations  of  Corn  Breeding. 
Bulletin  No.  132.     The  Effect  of  Selection  upon  Certain  Physical  Characters  in 

the  Corn  Plant. 


"Not  available  for  distribution 

61 


62 


BULLETIN  No.  132 


[February,  /pop. 


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